Earthquake crisis unveils the growth of an incipient continental fault system
Abstract
Large continental faults extend for thousands of kilometres to form boundaries between rigid tectonic blocks. These faults are often associated with prominent topographic features and they can produce large earthquakes. Here we present the first evidence of a major tectonic structure in its initial-stage, the Al-Idrissi Fault System (AIFS), in the Alboran Sea (Western Mediterranean). Until now, this fault system has always been described as a complex diffuse boundary between the Eurasia and Nubia plates. However, combining newly acquired high-resolution bathymetric and seismic reflection data, together with seismological analyses of the 25th January 2016 Mw 6.4 earthquake offshore Morocco - the largest event ever recorded in the area - we unveil a 3D geometry for the AIFS, which definitively corresponds to a crustal-scale boundary. We report evidence of left-lateral strike-slip displacement, characterize the fault segmentation and demonstrate that the AIFS is the source of the 2016 events. The occurrence of the Mw 6.4 earthquake together with historical and instrumental events supports that the AIFS is currently growing through propagation and linkage of its segments. Thus, the AIFS provides a unique model of the inception and growth of a young plate boundary fault system.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMOS54A..04G
- Keywords:
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- 3045 Seafloor morphology;
- geology;
- and geophysics;
- MARINE GEOLOGY AND GEOPHYSICS;
- 3070 Submarine landslides;
- MARINE GEOLOGY AND GEOPHYSICS;
- 4313 Extreme events;
- NATURAL HAZARDS;
- 7221 Paleoseismology;
- SEISMOLOGY